rick@digibd.com (Rick Richardson) (05/25/91)
bill@camco.Celestial.COM (Bill Campbell) writes: >I ran into a problem when printing faxes via the parallel port. >The system would slow down significantly while printing the >graphics files, and occassionally the VGA monitor would get sent An HP LJ2 will gobble up at least 5000 bytes/second from the parallel interface when transferring raster graphics. An LJ3 might go even faster, but I haven't measured one yet. I've measured the load on a 386/25 under these circumstances, and 50-60% of the cpu will be consumed during the transfer. On a 386SX, it was 80-90% of the CPU. This is one reason that we put a buffered parallel port on the DigiCHANNEL FAX/1 and FAX/2 fax boards. With the buffered parallel port you can feed the printer as fast as it will accept data, and the CPU loading measures about 0.5%, two orders of magnitude in difference. BTW, the board doesn't need an interrupt. -Rick -- Rick Richardson Email: rick@digibd.com Senior MTS Fax: (612) 943-0803 DigiBoard, Inc. Tel: (612) 943-5383
mah@wu-wien.ac.at (Michael Haberler) (05/26/91)
Sounds like you talk about some PC Unix. To get rid of the parallel printing slowdown, discard the manufacturer's parallel drivers, and use one of those floating on the net. Most of manufacturer's drivers are one-character-per-interrupt style. I did that, and not only did print faster and with less overhead, it also freed the parallel port IRQ line. If you cant get hold of such drivers, I'll dig them out and mail them. - michael -- Michael Haberler mah@wu-wien.ac.at, mah@awiwuw11.bitnet University of Economics and Business Administration A-1090 Vienna, Augasse 2-6 Biz: +43 (1) 31336 x4796 Fax: 347-555 Home: +43 (1) 961-679 (voice & fax) D-Netz: +43 (663) 811-056